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TT: Fachverband Tiefe Temperaturen
TT 52: Frustrated Magnets: Strong Spin-Orbit Coupling
TT 52.9: Talk
Thursday, March 30, 2023, 17:15–17:30, HSZ 201
Triple-Q order in Na2Co2TeO6 from proximity to hidden-SU(2)-symmetric point — •Wilhelm Krüger1, Wenjie Chen2, Xianghong Jin2, Yuan Li2,3, and Lukas Janssen1 — 1Institut für Theoretische Physik and Würzburg-Dresden Cluster of Excellence ct.qmat, TU Dresden, 01062 Dresden, Germany — 2International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China — 3Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
In extended Heisenberg-Kitaev-Gamma-type spin models, hidden-SU(2)-symmetric points are isolated points in parameter space that can be mapped to pure Heisenberg models via nontrivial duality transformations. Such points generically feature quantum degeneracy between conventional single-Q and exotic multi-Q states. We argue that recent single-crystal inelastic neutron scattering data place the honeycomb magnet Na2Co2TeO6 in proximity to such a hidden-SU(2)-symmetric point. The low-temperature order is identified as a triple-Q state arising from the Néel antiferromagnet with staggered magnetization in the out-of-plane direction via a 4-sublattice duality transformation. This state naturally explains various distinctive features of the magnetic excitation spectrum, including its surprisingly high symmetry and the dispersive low-energy and flat high-energy bands. Our result demonstrates the importance of bond-dependent exchange interactions in cobaltates, and illustrates the intriguing magnetic behavior resulting from them.